Improved shock absorbing and cushioning device



March 30, 1954 A. P. FlTz JOHN IMPROVED SHOCK ABSORBING AND CUSHIONING DEVICE Filed oct. s1, 195.0

. .ZZ/7 s, 1 i 4m 1 l auf.. QI@ y, y i .63 VW w/ x f 4 2 Patented Mar. 30, 1954 UNITED STATES IMPROVED SHOCK ABSORBING AND CUSHIONING DEVICE Arthur Percy Fitz John, Sheil'ield, England, as-

signor of one-half to George Turton Flatts & Company Limited, Wincobank, Sheiiield, England, a company of Great Britain and Northern Ireland Application October 31, 1950, Serial No. 193,103

Claims priority, application Great Britain November 4, 1949 Claims. (Cl. 267-65) This invention relates to shock absorbers employing a cylinder and piston assembly with fluid as the cushioning medium.

The invention has for one of its objects the provision of an efficient shock absorber in which the cylinder and piston assembly provides pressure fluid chambers in the cylinder one each at the front and rear of the piston for cushioning movement of said piston, said chambers being sealed from one another by an annular oil sealing chamber between the piston and the surrounding wall of the cylinder, the chamber at the rear of the piston communicating with a pressure fluid reservoir extraneous to the cylinder, a pressure responsive member being associated with and movable relative to the piston and being subject to pressure of fluid in the chamber at the front of the piston and to the oil in the annular oil sealing chamber, means being provided on the cylinder and the piston permitting anchoring thereof to separate bodies for relative movement of said cylinder and piston.

The annular oil sealing chamber may be formed by a circumferential recess in the piston in conjunction With the surrounding wall of the cylinder, said recess being provided between spaced mechanical sealing members accommodated in annular grooves in the piston.

Alternatively said annular chamber may be formed by spaced mechanically sealed annular members around the piston spacing said piston from the surrounding wall of the cylinder.

The pressure-responsive member may be displaceable directly against the liquid sealing medium in the annular chamber or against liquid sealing medium contained in a reservoir chamber or passages provided in the main piston and communicating with the annular chamber.

The pressure responsive member may function as an unattached component of the piston and may comprise an auxiliary piston displaceably and sealingly housed in the main piston in a chamber in the end face thereof exposed to the uid, said chamber forming part of a reservoir containing oil sealing medium in open communication with that in the annular chamber.

The oil reservoir chamber in the main piston may be filled from a passage leading thereto from a filling orifice in the main piston accessible through the cylinder or exteriorly thereof, said orifice being provided with a non-return valve. Alternatively, the oil reservoir chamber may be filled from an external reservoir from which the oil is admitted into the cylinder behind the main piston and conveyed therefrom to the oil reservoir chamber by passages in the main piston.

A coil spring may be provided in the reservoir chamber bearing against the end thereof and the auxiliary piston.

In an alternative construction, the pressure responsive member may constitute an annular auxiliary piston displaceably and sealingly housed between the main piston and the cylinder wall said annular auxiliary piston forming, in association with a displaceable or xed sealingly housed ring around, or integral or attached flange on, the piston or the cylinder, the mechanically sealed end walls of the annular chamber, a coil spring being located in said chamber, if desired, bearing against said end walls thereof.

Referring to the diagrammatic drawings filed herewith:

Fig. 1 is a sectional elevation of one form of shock absorber made according to this invention.

Fig. 2 is a sectional elevation of a modified form of shock absorber.

Fig. 3 is a sectional elevation of a still further modified form of shock absorber.

Referring to Fig. 1 a cylinder I0 is provided with a piston II reciprocable therein and adapted to compress fluid for example, air, in that section I2 of the cylinder which constitutes an air chamber at the front of the piston; that section 6I of the cylinder II) at the rear of the pis'- ton is filled with oil to constitute an oil chamber closed by the end member 62 of the cylinder, said end member being provided with sealing rings S3 between it and the piston rod 64. The oil chamber 6I is maintained full of oil by an extraneous oil reservoir 65 and pipe (i6, the oil in the reservoir being under pressure of air therein. The piston II is provided with annular grooves I3 accommodating sealing rings I4, one at either side of a recessed part of the piston which forms an annular oil sealing chamber I5 in conjunction with the surrounding wall of the cylinder Il! said annular oil sealing chamber being thereby mechanically sealed by one of the rings I4 from the air chamber I2.

Provided in the front end of the main piston II is a chamber I6 constituting an oil reservoir chamber which communicates with the annular oil sealing chamber I5 by radial ports I'I and with the oil chamber 5I by an oil supply passage 6G in the main piston I I.

` Displaceably held in the outer end of the oil reservoir chamber I6 is an auxiliary piston 20 exposed to the opposing pressures in the oil chamber BI and the air chamber I2 and adapted for movement responsively on difference arising in the opposing pressures of the oil and air said auxiliary piston 20 functioning as an unattached component of the main piston II. The auxiliary piston is provided with sealing rings 2| sealing the reservoir chamber I6 from vthe air chamber I2 of the cylinder. Inward movement of the auxiliary piston is restrained by a coil spring 22.

The air chamber I2 of the cylinder yis provided with an inlet 23 fitted with a non-return valve 24 through which air is pumped into said chamber.

The outer end of the piston rod SII-and the outer end G'I of the cylinder are provided respectively with eye lugs 68, 69 respectively for attachment of the device between two relatively moveable parts, such, for example, as between a vehicle chassis and axle box or like part associated with a road wheel, for damping shocks between the wheel and chassis. Thedevice may a-lso serve as a wheel-suspension means.

In operation when shock is applied to the main piston II or the cylinder III, the main piston moves forwardly into the cylinder, and

air in the air chamber I2 is compressed by the Vmain and auxiliary pistons II and 20rwith .the

result that pressure is set up in the air. Consequently, the auxiliary piston 28 is displaced vinwardly of the reservoir chamber I6 and thereby transmits pressure of the air to the oil in the reservoir chamber I 6, radialports II and annular oil sealing chamber I and also in the passage 60, oil chamber 6I at the rear of the piston, pipe 65 and external reservoir 65, thereby setting Aup an opposing pressure in the oil in the annular oil sealing chamber I5 substantially equal to the pressure of the air in the air chamber I2 of the cylinder and setting up a pressurebalanced seal between the oil and the air which prevents compressed air escaping past the piston.

On the forward stroke of the main piston, relative movement of the main piston to the cylinder and of the parts with which the piston and cylinder are respectively associated, is damped by the air in the chamber I2 whilst on the return stroke of the piston II such relative movement is damped by the oil in the oil chamber 6I which is under opposing pressure of air in the closed reservoir 65.

Fig. 2 shows an alternative construction of shock absorber similar to that shown in Fig. 1 with the exception that the oil in the reservoir chamber I5, radial ports Il and annular oil sealing chamber I5 is isolated from the oil in the oil chamber 6I at the rear of the piston, pipe 86 and external reservoir 65, oil being supplied to the reservoir chamber I6, ports II and annular oil sealing chamber I5 through a nonreturn valve I9, provided inthe piston rod exteriorly of the cylinder I0, and supply passage I8 communicating the non-return valve I9 with the reservoir chamber I6. Eye lugs 68,69 are provided as before for attachment of the device between two relatively movable members.

The operation of the device is substantially the same as that of the device of Fig. l except that, there being no communicating passage between the reservoir chamber I6 and the oil chamber lrdisplacement of the auxiliary piston by compressed air in the air chamber I2 'is transmitted only to the oil in the reservoir cham- 'ber IE, ports II and annular oil sealing chamber `I5 on theV forward'stroke of the main piston,

vis expelled from the oil chamber 6I external closed reservoir to compress the air 'reservoir would bean air reservoir.

oil being merely drawn into the oil chamber 6I from the external reservoir 65 during such forward stroke of the main piston. On the return stroke of the main piston, some of the oil to the therein and thereby apply pressure to the oil -in the `chamber 6I to damp the return stroke of the main piston.

Fig. 3 shows a` further alternative construction of shock absorber, in which the main piston II is spacedfrom the surrounding wall of the cylinder I0 by-two interposed ring members 30 and 3i spaced apart to provide the interposed vringf'members 30 .and 3I spaced apart to providethe annular oil sealing chamber I5, said ring members carrying sealing rings 32 and 33 contacting the piston and cylinder respectively and mechanically sealing the annular oil sealing chamber I5 from the air chamber I2 and from oil in the chamber 6I at the rear end of the cylinder behind the piston. y

The ring members 3i) and 3| are retained around the mainpiston by shoulders 34 and 35 respectively, the shoulder 34 being formed by a recessed part of the .main piston, and the shoulder 35 being provided by a detachable end plate 36 secured 'tov the main piston.

The annular chamber I5 is filled with oil pumped thereinto through the passages 4I from the passage 3l' and non-return valve 38 provided in the piston II exteriorly of the cylinder and air is pumped into the cylinder chamber I2 through the inlet 23 and non-return valve 24.

The annular ring member 3l constitutes the displaceable member responsive to the opposing pressures of the oil and air and functions as an unattached componenty of the mainvpiston in the form of an auxiliary annular piston, and a coiled spring 39 may be interposed between the two members 3G and 3l.

The piston and cylinder are, as before, provided with eye lugs (not shown) for attachment of the device between relatively movable members.

The chamber 6I is lled with oil supplied thereto through piping 56 from an external reservoir (not shown) similar to that described with reference to Fig. 1

In operation, when shock is applied to the main piston or cylinder, the main piston moves forwardly into the cylinder, and airin Vthe chamber I2 is compressed by themain and auxiliary pistons II andv 3I, with the result that pressure is set up inthe air tending to overcomev the pressure in the oil. Consequently, the auxiliary annular pistoni is displaced inwardly into the annular Vchamber I5 and thereby transmits pressure of thev air to the oil therein and in the passages 4I and 3l, thereby setting up an opposing pressure in the oil in the annular chamber I5 substantially equal to the pressure of the air in vthe chamber I2 of the cylinder, and setting upa pressure-balanced sealbetween theoil and the air which prevents compressed air escaping past the piston.

.The compression of the air in the chamber I2 during the forward stroke of they main piston has a damping effect upon thepiston. The return stroke ofthe piston is, as previously described with reference to Fig.l 1,dampedby the oil in the chamber 6I at the rear of thepiston.

Instead of the chamber 6I in Figs. 1, 2 and 3 being supplied with oil from the reservoir 65, it maybe supplied with'ar 'in which case said Alternatively, whcreair4 is used -insteadof o'il in' the chamber 6i, said chamber may be open to atmosphere by providing a restricted air inlet, the arrangement being such that the air drawn into the chamber 6l at the rear of the piston 6d on the forward stroke thereof, Would serve to damp recoil of the piston owing to exhaust of the air through the air inlet being restricted.

Further, instead of the piston 64 and cylinder I0 being provided with the eye lugs 68, other convenient means of anchorage to relatively movable members may be provided.

What I claim and desire to secure by Letters Patent is:

l. A shock absorbing unit comprising a cylinder, a piston in the cylinder dividing said cylinder into pressure fiuid chambers at the front and rear of said piston, an annular oil sealing chamber between the piston and the surrounding Wall of the cylinder, a pressure responsive member associated with and movable relative to the piston, one 'face of said member being exposed to the pressure fluid chamber in the cylinder at the front of the piston and an opposite face being exposed to the oil sealing chamber, apressure duid reservoir extraneous to the cylinder communicating with the pressure fluid chamber at the rear of the piston, a valve controlled pressure iiuid inlet to the other of said chambers, an oil inlet in the piston communicating with the oil sealing chamber, and means on the piston and the cylinder permitting anchoring thereof to separate bodies for relative movement of said cylinder and piston.

2. A shock absorbing unit comprising a cylinder, a piston in the cylinder dividing said cylinder into pressure fiuid chambers at the front and rear of said piston, an annular oil sealing chamber between the piston and the surrounding wall of the cylinder, a pressure responsive member slidably accommodated in the `front end face of the piston axially thereof and having remote faces exposed on the one hand to the pressure uid chamber at the front of the piston and on the other hand to the oil sealing chamber, a pressure fluid reservoir extraneous to the cylinder communicating with the pressure iiuid chamber at the rear of the piston, a valve controlled pressure duid inlet to the other of said chambers, an oil inlet in the piston communicating with the oil sealing chamber, and means on the piston and the cylinder permitting anchoring thereof to separate bodies for relative movement of said cylinder and piston.

3. A shock absorbing unit comprising a cylinder, a piston in the cylinder dividing said cylinder into an air chamber at the front and an oil chamber at the rear of said piston, an annular oil sealing chamber between the piston and the surrounding wall of the cylinder, a pressure responsive member slidably accommodated in the front end `face of the piston axially thereof and having remote faces exposed on the one hand to the air chamber at the front of the piston and on the other hand to the oil sealing chamber, an oil reservoir extraneous to the cylinder and communicating with the oil chamber thereof, a valve controlled air inlet to the air chamber, an oil passage in the piston communicating with the oil chamber and the oil sealing chamber and means on the piston and the cylinder permitting anchoring thereof to separate bodies for relative movement of said cylinder and piston.

4. A shock absorbing unit comprising a cylinder, a piston in the cylinder dividing said cylinder into an air chamber at the front and an oil chamber at the rear of said piston, an annular oil sealing chamber between the piston and the surrounding wall of the cylinder, a pressure responsive annular member slidably accommodated around the piston between it and the cylinder and forming one end Wall of the oil sealing chamber exposed to the air chamber, an annular member also around the piston and forming the other end wall of the oil sealing chamber exposed to the oil chamber of the cylinder, an oil reservoir extraneous to the cylinder and communicating with the oil chamber thereof, a valve controlled air inlet to the air chamber, an oil inlet in the piston communicating with the oil sealing chamber, and means on the piston and the cylinder permitting anchoring thereof to separate bodies for relative movement of said cylinder and piston.

5. A shock absorbing unit comprising a cylinder, a piston in the cylinder dividing said cylinder into an air chamber at the front of the piston and an oil chamber at the rear of said piston, an annular oil sealing chamber between the piston and the surrounding Wall of the cylinder, sealing rings in the piston sealing the air chamber from the oil chamber of the cylinder and the oil sealing chamber, a pressure responsive member associated with and movable relative to the piston, one face of said member being exposed to the pressure fluid chamber in the cylinder at the front of the piston and an opposite face being exposed to the oil sealing chamber, a pressure fluid reservoir extraneous to the cylinder communicating With the pressure uid chamber at the rear of the piston, a valve controlled pressure fluid inlet to the other of said chambers, an oil inlet in the piston communicating with the oil sealing chamber, and means on the piston and the cylinder permitting anchoring thereof to separate bodies for relative movement of said cylinder and piston.

ARTHUR PERCY FITZ JOHN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,220,630 Hayes Mar. 27, 1917 1,680,890 Laugaudin Aug. 14, 1928 1,984,144 Laugaudin Dec. 11, 1934 2,053,053 Swalm Sept. 1, 1936 2,604,320 Hoare July 22, 1952 FOREIGN PATENTS Number Country Date 655,224 Germany Jan. 11, 1938 

